TypeError: expected string or buffer in Google App Engine's Python

TypeError: expected string or buffer in Google App Engine's Python

I want to show the content of object by using the following code :
def get(self):
url="https://www.googleapis.com/language/translate/v2?key=MY-BILLING-KEY&q=hello&source=en&target=ja"
data = urllib2.urlopen(url)
parse_data = json.load(data)
parsed_data = parse_data['data']['translations']
// This command is ok
self.response.out.write("<br>")
// This command shows above error
self.response.out.write(str(json.loads(parsed_data)[u'data'][u'translations'][u'translatedText']))
But the error "TypeError: expected string or buffer" appears in the line :
self.response.out.write(str(json.loads(parsed_data)[u'data'][u'translations'][u'translatedText']))
or
self.response.out.write(json.loads(parsed_data)[u'data'][u'translations'][u'translatedText'])
I'm new in Python, IDE : IDEA IntelliJ, localhost,
please tell me,
Thanks,